Indices for evaluating a lens performance include an MTF (Modulation Transfer Function). The MTF represents, as a spatial frequency characteristic, an extent at which a contrast possessed by an object can be faithfully reproduced to know a lens performance. The spatial frequency indicates the number of patterns included per [mm]. In a so-called MTF curve, an axis of abscissas indicates the spatial frequency and an axis of ordinates indicates a value of the contrast.
There has been known an MTF measuring system for evaluating a lens performance by utilizing an MTF curve (for example, see Patent Document 1). The Patent Document 1 has disclosed an MTF measuring system for calculating an MTF to be an index for evaluating a lens performance to acquire MTF data based on object image data obtained by photographing an object through a lens, and evaluating the lens performance through an MTF curve represented by MTF curve image data generated from the MTF data.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2002-350285